1. Field of the Invention
This invention relates to gas flow amplifiers of the type which employ a high pressure, relatively low volume primary gas flow to induce additional secondary gas flow at a net lower pressure.
2. Description of the Prior Art
In the typical prior art gas flow amplifier, as illustrated for example in FIG. 1, a housing 10 has an inlet port 12, an outlet port 14, and inner and outer wall portions 16,18 defining a manifold chamber 20. Nozzle openings 22 are drilled into the inner wall 16 at circumferentially spaced locations surrounding the outlet port 14, and an inlet fitting 24 is provided in the outer wall 18. A hollow truncated conical diffuser 26 is attached to the housing 10 in communication with the outlet port 14.
A relatively high pressure and low volume primary gas such as for example compressed air or steam is fed into the chamber 20 via inlet fitting 24. The primary gas exits chamber 20 via the nozzle openings 22 and is injected in a converging pattern into the small diameter end of the diffuser 26. The thus injected primary gas entrains a flow of ambient secondary gas into the diffuser via the inlet port 12.
The arrows in FIG. 1 schematically depict the directions of gas flow, and the broken lines illustrate velocity profiles. It will be seen that the entrained ambient secondary gas enters the housing 10 with an essentially laminar velocity flow profile 28. However, at the inlet end of the diffuser, the secondary gas mixes with the injected primary gas with accompanying extreme turbulence, and with immediate separation of flow as at 30 due to premature expansion in the diverging diffuser. As the combined flow of primary and secondary gases continues along the diffuser, a laminar flow pattern 32 begins to re-establish itself, but separation continues as at 34. The combined gas flow ultimately exits from the enlarged end of the diffuser with a somewhat unstable laminar flow pattern, and with some intermittent separation still in evidence as indicated for example at 36.